Clean wind and solar energy are crucial allies in the fight against global warming. But critics often point to the need for costly energy storage systems for when the wind isn’t blowing and the sun isn’t shining.

The results, published in Nature Climate Change by researchers from the National Oceanic and Atmospheric Administration (NOAA), show that solar and wind energy would reduce the U.S. electric sector’s carbon dioxide emissions by up to 80 percent compared to 1990 levels. The key technology to enable this will be a national electricity grid of high-voltage direct-current transmission lines that span the country. Today, the grid is divided regionally. A national system would make sure renewable resources are connected to high-energy-demand areas.

Alexander MacDonald, Christopher Clack, and their colleagues at NOAA designed a new model called the National Electricity with Weather System model to assess wind and solar generation at 13-km horizontal resolution and 1-hour temporal resolution. Compared to previous models that others have developed to study the electrical power system, theirs uses higher resolution weather data, broad geographic areas, and extended time periods, the researchers say in the paper.

The team used historical and projected carbon dioxide emission and electricity cost data from the International Energy Agency. They ran three different scenarios on the model. One assumed renewables at a low cost and natural gas at a high cost; the another assumed high cost of renewable energy and low-cost natural gas; while the third assumed mid-range prices for both.

All three scenarios resulted in reduced carbon emissions and electricity price. The greatest reduction in carbon emissions (78 percent below 1990 levels) came from the low-cost renewables scenario, with average electricity prices at 10 cents per kilowatt-hour. The high-cost renewables scenario reduced carbon emissions by 33 percent and showed an electricity cost of 8.6 cents/kWh.

The researchers also looked at land and water use. In the model’s high- renewable scenario, wind and solar generators take up less than 0.1 percent of land in the continental United States. And the use of wind and solar energy reduces water consumption in the electricity sector by 65 percent. The model didn’t allow renewables development on protected lands, urban areas and steep slopes.

Even then, could such a dramatic overhaul of the U.S. electrical power system be possible? It will face “formidable challenges” the team says. But the country has faced, and solved, similar challenges before. We got the transcontinental railroads and the interstate highway system as a result. Solving the power system-transformation challenge could have an even bigger impact. – Prachi Patel | 28 January 2016